(Received 13 November 2012;accepted 15 November 2012;online 24 November 2012)

In the title compound, [Cu(C4H2O4)(C11H9N3O)2(H2O)]n, CuII ions on crystallographic twofold rotation axes are coordinated in a square pyramidal environment by two trans O atoms belonging to two monodentate fumarate anions, two trans isonicotinamide pyridyl N-donor atoms from monodentate, pendant 3-pyridyl­isonicotinamide (3-pina) ligands, and one apical aqua ligand, also sited on the crystallographic twofold rotation axis. The exobidentate fumarate ligands form [Cu(fumar­ate)(3-pina)2(H2O)]n coordination polymer chains that are arranged parallel to [001]. In the crystal, these polymeric chains are anchored into supra­molecular layers parallel to (100) by O—H⋯O hydrogen bonds between aqua ligands and unligating fumarate O atoms, and N—H⋯O(=C) hydrogen bonds between 3-pina ligands. In turn, the layers aggregate by weak C—H⋯N and C—H⋯O hydrogen bonds, affording a three-dimensional network.

Related literature

For the preparation of 3-pyridyl­isonicotinamide, see: Gardner et al. (1954). For the preparation of other dicarboxyl­ate coordination polymers containing 3-pyridyl­isonicotinamide, see: Kumar (2009).

In comparison to divalent metal coordination polymers containing rigid rod dipyridine ligands such as 4,4'-bipyridine, related materials containing the kinked dipodal ligand 3-pyridylisonicotinamide (3-pina) are much less common (Kumar, 2009). The title compound was obtained as blue crystals through the hydrothermal reaction of copper nitrate, fumaric acid, and 3-pina.

The asymmetric unit of the title compound contains a divalent copper atom and an aqua ligand on a crystallographic twofold rotation axis, a 3-pina ligand, and one half of a fumarate ligand whose centroid rests on a crystallographic inversion centre. The copper atom is square pyramidally coordinated (Fig. 1), with the basal plane containing trans isonicotinamide pyridyl N atom donors from two 3-pina ligands and trans O atom donors from monodentate carboxylate groups belonging to two fumarate ligands. The aqua ligand is located in the apical position.

All H atoms bound to C atoms were placed in calculated positions, with C—H = 0.95 Å, and refined in riding mode with Uiso = 1.2Ueq(C). The H atom within the amide group of the 3-pina ligand was found in a difference Fourier map, restrained with N—H = 0.90 (2) Å and refined with Uiso = 1.2Ueq(N). The H atoms within the aqua ligand were found in a difference Fourier map, restrained with O—H = 0.85 (2) Å and refined with Uiso = 1.2Ueq(O).

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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